Might be a result of allowing links after 10 posts, revenue share after 50, revenue sharing based on posts. Reward volume of posts w/o any quality judgement and you get loads of small, quick, low content posts. Not surprising.
I simply don't care since PR is useless and backlinks are taken in consideration even without those updates Jully something like this will be the next one
It will definitely be some time in late June to early July and then October for the next one. I predicted both of the updates so far this year 100% accurate. I really don't give a hoot about PR itself but I do watch for updates because that's when it's time to start checking your SERPS.
Thats not true as some sites reported there was a PR changed in late Feb or early March... cant remember when. My PR on my one site in Jan was PR2. Now its PR3 after the 2nd PR change. Some sites were effected, and some weren't.